1. Field of the Invention
The invention relates generally to circuit interrupters and, more particularly, to circuit interrupters operating under short circuit conditions to limit the flow of current through the interrupter to a value lower than the available fault current which the circuit is capable of supplying.
2. Description of the Prior Art:
Circuit breakers are widely used in industrial, residential, and commercial installations to provide protection against damage due to overcurrent conditions. As the usage of electrical energy has increased, the capacity of sources supplying this electrical energy has increased correspondingly. Therefore, extremely large currents can flow through distribution circuits should a short circuit condition occur. Under these conditions conventional circuit interrupters are incapable of preventing severe damage to apparatus connected downstream from the interrupter.
Current limiting circuit interrupters were developed to provide the degree of protection necessary on circuits connected to power sources capable of supplying very large fault currents. One type of circuit interrupter provides such current limiting action by operating to achieve extremely rapid separation of the contacts during short circuit conditions. This action produces an arc voltage across the contacts which quickly approaches the system voltage, thus limiting the current flow between the contacts. Although the performance of prior art current limiting circuit interrupters of this type was adequate in certain applications, it would be desirable to provide a circuit breaker providing an even higher degree of current limiting action. Furthermore, prior art current limiting circuit interrupters were expensive to manufacture and bulky in size, thus limiting their applicability. It would therefore be desirable to provide a current limiting circuit interrupter offering increased performance in a smaller size at a more economical cost.